1. Field of the Invention
The present invention relates to an optical sensor holder for holding an optical sensor at a predetermined position to detect a light beam.
2. Description of the Prior Art
As a conventional type optical sensor holder, an optical sensor holder disclosed in JP-A-60-217545 is known.
In this optical sensor holder, an optical sensor is inserted through an opening formed on backside of the holder, and the sensor unit on the optical sensor is positioned face-to-face to a window so that the sensor unit is exposed to light. By fixing a printed circuit board using screws on the opening on backside of the holder, the incidence of the light into the holder from portions other than the window is prevented.
As another type of optical sensor holder, an optical sensor holder disclosed in Japanese Utility Model 4-111019 Laid-Open is known. In this case, a hood is provided on a window of a holder, and only a light beam entering from the direct front of the tip of the sensor unit can be detected.
In the conventional type optical sensor holders as described above, there have been the following problems:
In case of the former, the printed circuit board must be fixed by screws to prevent the incidence of the light into the holder from portions other than the window. This means that the number the component parts must be increased and complicated assembling procedure is needed.
In case of the latter, no consideration is given on the light beam entering the holder from portions other than the window. If the light beam enters from portions other than the window, the optical sensor may erroneously detect the light.
It is an object of the present invention to provide an optical sensor holder, in which only the light coming from a predetermined direction can enter and there is no need to increase the number of component parts and to use complicated assembling procedure.
In a concrete arrangement example, the optical sensor holder of the present invention comprises:
a holder main unit made of synthetic resin and having an opening formed on backside thereof where an optical sensor can be inserted, a window where a sensor unit arranged on the optical sensor is faced to outside on upper portion of the front side, a partition plate formed toward backside and for dividing inner space of the holder main unit in lateral direction so that a pair of metal terminals of the optical sensor can be moved away from each other in lateral direction in the holder main unit, a positioning pin projected from inner part of the opening toward backside, and a positioning pin integrally projected from the bottom surface for positioning with respect to a base plate and said positioning pin being inserted into a positioning hole formed on the base plate;
a cover unit made of synthetic resin, having a positioning hole for receiving the positioning pin and mountable on said opening so that the sensor unit can be covered from backside;
an arm made of synthetic resin and integrally molded as bendable between the tip of the holder main unit and the tip of the cover unit; and
a leg structure having a pair of leg units extended approximately in parallel and in the same direction to be separated from the holder main unit, having pawls to be engaged with mounting holes formed on the base plate and arranged on forward end thereof to be separated from each other, and said leg units being bendable in directions to be moved closer to each other.
In an essential arrangement of the optical sensor holder, the optical sensor holder comprises:
a holder main unit, having an opening for receiving an optical sensor on backside thereof and a window where a sensor unit provided on the optical sensor is faced to outside on front side;
a cover unit mountable on said opening so that the sensor unit can be covered from backside; and
a connection unit for connecting said holder main unit with the cover unit.
In the present invention with the arrangement as described above, the optical sensor is inserted through the opening on the backside of the holder main unit. The sensor unit provided on the optical sensor is positioned face-to-face to a window formed on the holder main unit, and the sensor unit is exposed to the light.
A cover unit connected to the holder main unit via a connection unit is mounted on the opening so that the sensor unit is covered from the backside and the light does not enter the holder main unit from portions other than the window.
As a result, in the optical sensor holder, the light enters only through the window, and the sensor unit detects this incident light. Therefore, there is no possibility that the sensor unit erroneously detects the light entering from portions other than the window.
As explained above, it is possible according to the present invention to provide an optical sensor holder, in which only the light from a predetermined direction can enter, and this means that there is no need to increase the number of component parts and to use complicated assembling procedure.
The holder main unit and the cover unit are connected with each other via the connection unit, and there is no need to have component parts for individual purpose. This means that there is no need to increase the number of component parts and to use complicated procedure to assemble the cover unit with the holder main unit.
As an example of additional arrangement to provide the holder main unit with the optical sensor at a predetermined point, the holder main unit can be also be designed with a leg structure mountable on the base plate.
In the invention with the arrangement as described above, the holder main unit with the optical sensor accommodated in it can be fixed on the base plate by mounting the leg structure on the base plate.
According to the present invention, the arrangement of the holder main unit at a predetermined point can be integrally designed with the holder.
As described above, when the holder main unit is provided with the leg structure, it is convenient because it can be easily mounted on the base plate. However, this is only an example. From the viewpoint that the optical sensor is accommodated in the holder main unit in such manner that the light does not enter from the portions other than the window, it is possible to use a mounting member prepared for each individual purpose or to form a mounting structure on the base plate side. Because the holder main unit of the present invention is not limited to the one fixed on the base plate, it may be fixed on a cabinet.
As an arrangement example of the leg structure, it may be designed in such manner that the leg structure comprises a pair of leg units extended approximately in parallel and in the same direction to be separated from the holder main unit, having pawls to be engaged with mounting holes formed on the base plate and arranged on forward end thereof to be separated from each other, and said leg units being bendable in directions to be moved closer to each other.
In the invention with the arrangement as described above, the pawls are formed on the forward end of a pair of leg units extended approximately in parallel and in the same direction to be separated from each other and arranged on the side to be separated from the holder main unit, and the pawls are pressed against opening edges of the mounting holes formed on the base plate. As a result, the leg units can be inserted into the mounting holes when the leg units are bent to directions to move closer to each other.
When the pawls are inserted into the mounting holes and are projected on opposite surface of the base plate, each of the leg units is restored to the initial position in the directions to be separated from each other, and the pawls are engaged with the opening edges on the opposite side of the mounting holes.
As described above, it is possible according to the present invention to provide the leg structure by merely adding a simple arrangement to the holder main unit.
As an example of additional arrangement of the holder main unit, the invention also provides an optical sensor holder, wherein said holder main unit comprises a positioning pin integrally projected toward extending direction of said leg unit so that positioning can be performed with respect to the base plate, said positioning pin being inserted into a positioning hole formed on said base plate.
In the invention with the arrangement as described above, when the leg units are mounted on the base plate, the positioning pin integrally projected from the bottom surface of the holder main unit to the side where the leg units are extended is inserted into the positioning hole formed on the base plate.
Then, the positioning pin is positioned at a point where the positioning hole is formed, and the positioning of the holder main unit can be achieved.
As described above, it is possible according to the present invention to arrange the holder main unit at any desired point on the base plate.
In an arrangement example of the connection unit, the connection unit has flexibility so that it can be bent toward backside of the holder main unit.
In the invention with the arrangement as described above, the cover unit is connected with the holder main unit via the connection unit which can be bent toward backside of the holder main unit. Thus, in case the optical sensor holder is molded, for instance, it is possible to arrange the holder main unit, the connection unit and the cover unit approximately on the same plane. This is because, when the optical sensor is inserted into the holder main unit, the cover unit can be moved toward backside of the holder main unit and can be mounted on the opening of the holder main unit.
Then, it is possible to simplify the structure of a die to mold the optical sensor holder.
As described above, it is possible according to the present invention to simplify the structure of the die used for the molding of the optical sensor holder.
Also, in case the cover unit is mounted on the opening of the holder main unit, it is possible to have additional arrangement so that the sensor unit can be perfectly covered. As an example, it is arranged in such manner that a positioning pin projected to backside is provided in inner part of the opening of the holder main unit, and that said cover unit comprises a positioning hole where the positioning pin can be inserted to perform positioning.
In the invention with the arrangement as described above, when the cover unit is mounted on the opening of the holder main unit, the positioning pin projected from inner part of the opening of the holder main unit toward backside is passed through the positioning hole formed on the cover unit, and the position of the cover unit is determined.
Then, the position of the cover unit mounted in the opening is deviated and a gap is generated in the opening, and it is possible to prevent the incidence of the light into inner space of the holder main unit through the opening.
Thus, it is possible according to the present invention to perfectly prevent the incidence of the light through the gap formed between the cover unit and the opening of the holder main unit.
Further, the optical sensor usually comprises a pair of metal terminals, and these metal terminals must be accommodated in the holder main unit under the condition where the terminals are insulated from each other. In an additional arrangement to accommodate the metal terminals under the condition where the terminals are insulated from each other, a partition plate for dividing inner space of the holder main unit in lateral direction is formed in backward direction in inner part of the opening of the holder main unit so that a pair of metal terminals provided on the optical sensor can be moved away from each other in lateral direction in inner space of the holder main unit.
In the invention with the arrangement as described above, there is provided a partition plate formed from inner part of the opening of the holder main unit toward backside and to divide inner space of the holder main unit in lateral direction, and a pair of metal terminals are accommodated. Then, it is possible to prevent short-circuiting by separating the metal terminals away from each other in lateral direction of the holder main unit.
As described above, it is possible according to the present invention to accommodate the metal terminals of the optical sensor into the holder main unit under the condition where the metal terminals are insulated from each other.
Other and further objects, features and advantages of the invention will appear more fully from the following description.